In the poultry industry, it is accepted that 5 to 30% of eggs are not fertile or viable, which leads to the absence of hatching of a chicken. To overcome this problem, some techniques have been developed for discriminating, for the purpose of elimination, between fertilized (having an embryo) and non-fertilized eggs. A currently known technical solution for discriminating between fertilized eggs is based on the use of optics or various luminous sources particularly laser as described in FR0512998.
This egg discriminating step is commonly called “egg candling.” The elimination step of eggs identified as being non fertilized following the “candling” step is commonly called “removal” of eggs.
The combination of the “candling” and “removal” steps of eggs makes it possible to obtain a homogenous population of fertilized eggs likely to hatch into a chicken.
Techniques in embryology have made it possible to add various compounds beneficial to the chickens inside eggs, directly in the embryo or in the vicinity of the embryo. In particular, such beneficial compounds may result in improved growth of the chicken, such as by the prevention of illness, an increase in the percentage of hatched eggs, or even the improvement of the poultry's physical characteristics. The addition of compounds in the fertilized egg is commonly called in ovo treatment.
In the particular case of illness prevention, and more particularly in the case of vaccination, the in ovo treatment techniques based on the injection of the vaccine through the egg shell by needle are widely used. An injection system making the in ovo treatment possible while reducing the effect on embryos caused by the injection of the vaccine is described in patent FR1505870.
For economic reasons and in order to prevent any contamination risk linked to the treatment of the non fertilized eggs (there may be a risk of explosion or contamination due to the albumin contained in these eggs), it is preferable to carry out the in ovo treatment of fertilized eggs that are selected by a candling and removal step.
The economic viability of in ovo treatment mainly resides in the automation of the set of candling, removal and the actual treatment steps. Technical solutions of integration and automation of these steps have been described in patent FR2873894.
The currently available set of automated solutions for the candling and removal of eggs can lead to the random distribution of fertilized eggs spread out over an entire presentation tray. As a result, particularly complex and costly injectors for carrying out the in ovo treatment have been developed such as is described in WO06/078499.
Manual replacement of eggs on the presentation tray has also been utilized. In accordance with this technique, one or several operators may place eggs into the holes of the trays from which non fertilized eggs have been removed. This replacement step is commonly called “stabilizing.”
Manual “stabilizing,” however, may not be compatible with the processing rates which have been achieved through the automation of the “candling,” and “removal” steps.